[c-nsp] 802.1q - Max Number of Subinterfaces

[sthaug at nethelp.no]

> > Something to be aware of is the per-interface sub-interface limits for
> > the various cards.  Perhaps someone has a pointer to an official Cisco
> > document, but I *think* almost all of the FE/GE interfaces on the
> > 7200-series support up to 256 sub-interfaces.  Thus, you'd have to have
> > multiple interfaces to hit the chassis limit.
> 
> This matters.
> 
> I would like to terminate the vlans on a single g/f interface.  It doesn't 
> matter if it's a router or L2/L3 switch.

IDB limits are important. Also, for a switch, the max number of active
VLANs is relevant (this is often lower than 4K).

> Does the same limitation apply using SVI on a switch?

L3 switches often have lower limits than a router.

If you really want to terminate many thousand of VLANs in one box, you
should seriously consider an aggregation platform like the Cisco 10000
or Juniper ERX. As an example, the Juniper ERX-310 (3U) can terminate
16K IP interfaces (and a corresponding number of VLANs) in one box, with
hardware based forwarding. See the "system maximums" section at

http://www.juniper.net/techpubs/software/erx/junose72/sw-rn-erx723/html/sw-rn-erx723-app-A-sysmax.html

Steinar Haug, Nethelp consulting, sthaug at nethelp.no